The proposed research is directed at gaining a better understanding of the reason why tumors or normal tissues have a differential pattern of growth and development depending on where in the body they are located. Specific experiments are designed to: 1) characterize further the nature of regional differences seen when tumor cells are inoculated into various portions of the body; 2) determine the nature of regional effects that might be exerted on growth and differentiation of normal tissues; and 3) determine what metabolic or developmentally significant processes might be correlated with the observed regional effects in the hope that this would permit establishment of causal connections between those processes and the observed regional differences. Aside from the immediate practical implications resulting from the delineation of regional differences it is hoped that the experiments will provide basic insight into what may represent a critical control point regulating both normal and abnormal growth and development.